Bio balls...a thing of the past?

[Harold999]

That´s a type of mechanical filter in my eyes - a biological filter promotes microbes to grow and form biofilms. If a filtermath is in use - it need to be rather coarse (10 ppt) combined with a fast flow through it in order to work as a good biological filter.

Sincerely Lasse

My theory is that if a parasite lands in a biofilm and getting stuck there it will be eaten alive by the microbes.
Thick multiple layers of filtermaths/floss might achieve that.
The parasite gets stuck in it and it's bye bye.

If you only have a thin filtersock and some kind of ceramic stuff (pipes/blocks) in your sump (many people have that), the parasites can swim through it happily and come back in the tank.

 

[Belgian Anthias]

My theory is that if a parasite lands in a biofilm and getting stuck there it will be eaten alive by the microbes.
Thick multiple layers of filtermaths/floss might achieve that.
The parasite gets stuck in it and it's bye bye.

If you only have a thin filtersock and some kind of ceramic stuff (pipes/blocks) in your sump (many people have that), the parasites can swim through it happily and come back in the tank.

What parasites are you talking about? Those infecting fishes? Bacterial or multicellular? Viruses?
Talking about eaten alive it must be heterotrophs eathing them. Heterotrophic microbes mainly brake down organic waste and they use dissolved organics.

Mechanical filter substrate as diatomic earth may hold back most multicellular parasites and eggs and kill them not being able to fulfill their life cycle. But not all.
if you want to hold back parasites you also can use a mechanical mesh filter size smaller as the parasite and clean it to remove the parasites. One must be able to prevent clogging.
if you want to kill them you can use a good UV germicidal lamp able to produce at least 180 000 µW-s/cm².

But it may kill or hold back only what is present in the water passing by. it will not prevent parasites to develop in the tank.

 

[Belgian Anthias]

Good bio-filters will not hold back most parasites because the water must be able to penetrate freely, able to provide BOD ( biological oxygen demand). For example using moving bed bio-reactors.
For to be used in a sump, or better in a refuge, the best results may be achieved not using flow true filter beds but provide filter surface by hanging up the substrate, having a high water exchange rate with the water flowing around it., not true it. Such filter beds are only max +- 2,5 cm ( 1 inch) thick, using the surface of both sides. Using filter columns, rolls, +- 4 cm max diameter. Such filters do not clog easily due to accumulation of bio-waste as do bio-filters with flow true filter beds. Using flow around filters periphython may develop if there is enough light. Using flow true filters, this will clog the filter.

Using plastic bioballs as a substrate, degradable or not degradable, will not provide the carbonate source needed to compensate for alkalinity consumption of nitrification or and autotrophic denitrification taking place within the biofilm.
If carbonate based substrate is used the acids produced by the biofilm may be neutralized.